Impacts of inundation and drought on eukaryote biodiversity in semi‐arid floodplain soils

Abstract

Floodplain ecosystems are characterized by alternating wet and dry phases and periodic inundation defines their ecological character. Climate change, river regulation and the construction of levees have substantially altered natural flooding and drying regimes worldwide with uncertain effects on key biotic groups. In southern Australia, we hypothesized that soil eukaryotic communities in climate change affected areas of a semi-arid floodplain would transition towards comprising mainly dry-soil specialist species with increasing drought severity. Here, we used 18S rRNA amplicon pyrosequencing to measure the eukaryote community composition in soils that had been depleted of water to varying degrees to confirm that reproducible transitional changes occur in eukaryotic biodiversity on this floodplain. Interflood community structures (3 years post-flood) were dominated by persistent rather than either aquatic or dry-specialist organisms. Only 2% of taxa were unique to dry locations by 8 years post-flood, and 10% were restricted to wet locations (inundated a year to 2 weeks post-flood). Almost half (48%) of the total soil biota were detected in both these environments. The discovery of a large suite of organisms able to survive nearly a decade of drought, and up to a year submerged supports the concept of inherent resilience of Australian semi-arid floodplain soil communities under increasing pressure from climatic induced changes in water availability.

Tree diversity and species identity effects on soil fungi, protists and animals are context dependent

“…Based on our analysis of DNA and microbial biomass, the amount of cells and ribosomal DNA molecules of soil animals is in minority compared with that of bacteria and fungi, which is in agreement with previous studies targeting SSU and LSU (Baldwin et al, 2013;Ramirez et al, 2014;Tedersoo et al, 2015a). The fungal dominance could be related to the actual differences in the number of cells and/or copies of ribosomal DNA (Medinger et al, 2010;Vetrovsky and Baldrian, 2013).…”

Metatranscriptomic census of active protists in soils

“…The supergroup Amoebozoa was of particular interest, as no comprehensive molecular taxonomic analysis of this protist supergroup in soil exists to date because of PCR-primer biases (Baldwin et al, 2013;Bates et al, 2013). For this purpose, we constructed a high-resolution reference database and taxonomy of Amoebozoa (see Table 2 and Materials and Methods for details).…”

Effects of short-term flooding on aquatic and terrestrial microeukaryotic communities: a mesocosm approach

“…The soil community was strongly dominated by fungi, in particular ascomycetes, but cercozoans, ciliates and some algae were also part of the community. Community composition was therefore dominated by taxa typically reported for rivers (Gamier et al 1995 Crump et al 2012, Baldwin et al 2013, Geisen et al 2015, Grossmann et al 2016.…”

“…However, we suspect that fungi are overrepresented in the sequence libraries because specifically the reverse primers have originally been designed for fungi. Because fungi were expected to be a dominant component specifically in soil (O'Brien et al 2005, Barrios 2007, Baldwin et al 2013), a certain bias towards this group and a presumably good taxon coverage for this group was considered advantageous when selecting the primer set. In contrast, a low read abundance for e.g.…”

“…agricultural studies and mesocosm experiments leading to anoxic conditions in soil (Liesack et al 2000, Unger et al 2009b). These studies investigated plant and microbial communities in floodplain or riparian zones (Blom & Voesenek 1996, Beltman et al 2007, Kobayashi et al 2009, Baldwin et al 2013, Simoes et al 2013, effects of altered hydraulic conditions on fishes, invertebrates and the algae community in streams (Growns & Growns 2001, Anderson et al 2006, McKay & King 2006 or the effect of abiotic changes on the microbial communities in soils (Bossio & Scow 1995). However, most studies focused on one habitat type.…”